Gas turbine engines, such as turbofan gas turbine engines, may be used to power various types of vehicles and systems, such as aircraft. Typically, these engines include turbines that rotate at a high speed when blades (or airfoils) extending therefrom are impinged by high-energy compressed air. Consequently, the blades are subjected to high heat and stress loadings which, over time, may reduce their structural integrity.
To improve blade structural integrity, a blade cooling scheme is typically incorporated into the turbines. The blade cooling scheme is included to maintain the blade temperatures within acceptable limits. In some cases, the blade cooling scheme directs cooling air through an internal cooling circuit formed in the blade. The internal cooling circuit consists of a series of connected, serpentine cooling passages, which incorporate raised or depressed structures therein. The serpentine cooling passages increase the cooling effectiveness by extending the length of the air flow path. In this regard, the blade may have multiple internal walls that form intricate passages through which the cooling air flows to feed the serpentine cooling passages. The blade cooling scheme may also include platform cooling, in some cases. For example, openings may be formed through a turbine disk from which the blades radiate, and the openings may direct cool air from a cool air source onto a platform of the blade.
Although the above-described blade cooling scheme adequately cools the blades during engine operation, it may be improved. In particular, the openings for cooling the blade platform may be relatively difficult to configure and/or form for maximum effectiveness. Additionally, because blade airfoils are exposed to gases at high temperatures (e.g., temperatures greater than about 1100-1800° C.) and gases flowing at high velocities (e.g., with Mach numbers in the range of 0.3 to 1.3) during operation, cooling air directed to the blade platform may be stripped off. Moreover, hot flow path gases flowing along the blade airfoil may migrate to the platform, which may cause the platform to operate in temperatures that are higher than for which the platforms are designed. As a result, the blade and/or blade platform may be exposed to high thermal strains, which may result in thermo-mechanical fatigue.
Accordingly, it is desirable to have an improved blade platform configuration that reduces thermo-mechanical fatigue and other forms of distress, when exposed to high temperatures and high velocities. In addition, it is desirable to have an improved platform configuration that is relatively simple and inexpensive to implement and that may be retrofitted into existing engines. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.